[Racal] R1792 Display lighting tip required

[Dan Rae]

Peter Worrall, G4GJL wrote:

> I just recently became the owner of a backlit RA1792.
>
> Some of the bulbs have blown, and the previous owner let me have a 
> pack of replacement bulbs.
>
> Problem is how to get the display modules out in order to access the 
> bulbs....
>
> I realise I have to remove the front panel first, as the maintenance 
> manual says this. It is rather scanty on how to proceed beyond that!

You will have to remove the LCD displays to get at the bulbs, after 
removing the panel.  I have made tools to pull them from the blanking 
strips that go over unused computer slots, with the short part of the L 
shape cut down a bit and padded with a thin bit of rubber.  Gentle 
pulling at both ends should free the displays.  Make a note of which way 
round they are, although you can usually see the patterns by angling 
them right.  Actually the back lit ones are much easier to remove safely 
than the others due to the perspex (acrylic) diffuser on the back.

The bulbs ( 5 Volt, 60 mA) are wired in series pairs across the 9 Volt 
AC supply.   To get an evenly lit display you may need to replace both 
in a pair, even if one is good.

73
Dan
ac6ao / g3ncr